There is considerable interest in the field of audio signal processing to provide for systems which can efficiently deliver multiple channels of audio information. Systems which have more than one channel are attractive because they are capable of presenting more realistic three-dimensional sound fields than systems with only one channel. Within some limits, the ability to accurately reproduce three-dimensional sound fields increases as the number of channels increases. For example, some motion picture playback systems use four or more channels to reproduce a motion picture soundtrack. Current motion picture standards for future systems include five full-bandwidth channels and a sixth narrow-bandwidth channel for low-frequency effects. It is expected that soundtracks with four or more channels will be carried by video cassette tapes and optical discs as well. Proposed standards for Advanced Television (ATV) and High-Definition Television (HDTV) also include specifications for similar audio systems.